Nitride semiconductor light emitting devices are widely used in illuminating devices, video displays, signals transmission, and so on. In these applications, semiconductor light emitting devices having low operating voltages and high optical outputs are generally preferred.
In nitride semiconductor light emitting devices, it is common to provide a p-side electrode and an n-side electrode on a same side of a semiconductor laminate on a surface having a stepped portion, that is a surface with different levels, and use the other side of the laminate as the emission side (i.e., the light output side) of a light emitting device.
When charge carriers are intensively injected into a narrow area of a light emitting layer close to the p-side electrode and the n-side electrode, Auger non-radiative recombination and carrier overflow increases. For this reason, the luminous efficiency decreases, and thus high optical output is not obtained, and the operating voltage becomes higher.
Further, when carriers are concentrated in sub-portions of the light emitting layer, other problems may occur, for example, chromaticity is different between the central portion and peripheral portion of a chip, and color irregularity occurs.